Phone not registering over VPN

I’m testing out FreePBX and I have setup a site-to-site with one of my remote locations, VPN traffic is good on both sides, I can ping the phone from HQ and remote site can ping the FreePBX. I’m using a Yealink T20P, and I have set the remote local subnet in the SIP settings and allowed the remote local subnet to that extension. However while the phone will not register, I did install X-Lite on a workstation and it registered fine. Ami I just missing something?

I am having this exact same issue. Any chance you ever found a solution

I’ve a S700 sangoma ip phone.
I got an VPN ip on it.
but the account is not registered.
Seems to be close to your problem.